Hearth furnace



June 16, 1953 l. E. CUSHING ET AL HEARTH FURNACE Filed Oct. 30, 1950 pLI la:-

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IVAN E. CUSHING GIBBS M. SLAUGHTER ATTORNEY Patented June 16, 1953 HEARTH FURNACE Ivan E. Cushing and Gibbs M. Slaughter, Fort Worth, Tex., assignors to Acme Brick Company, Fort Worth, Tex., a corporation of Texas Application October 30, 1950, Serial No. 192,974

.3 Claims.

This invention relates to improvements in hearth furnaces, for heating boilers and the like. An object of the invention is to provide a hearth furnace which will supply a constant and even flow of heat to the boiler tubes or other'surfaces to be heated.

Another object of the invention is to provide a hearth arrangement whereby the ashes may be removed without disturbing the burning fuel pile.

.A further object of the invention is to rovide a hearth furnace for heating a boiler wherein the operating boiler pressure is maintained while fuel is beingadded to fuel pile, or while ashes are being removed therefrom.

, A further object of the invention is to provide ample storage space for unburned fuel within a hearth furnace, and which space not only positions the fuel for burning but dries the same as well. c

I These and other objects will become apparent from the following description and the accompanying drawings of an exemplary form of the invention.

Figure 1 is a schematic vertical sectional view of a hearth furnace and boiler assembly embodying the features of the invention. a

Figure 2 is a vertical sectional view taken on lines 22 of Figure 1 and showing the arrangement of the fuel pile in the hearth furnace.

v Figure 3 is a broken plan and sectional view of the furnace and showing the arrangement of the clean out doors with respect to sides of the fuel pile.

The present invention is directed to a hearth furnace construction wherein the fuel pile extends from one side of the hearth furnace to the other for providing a constant and even flow of heat to the surfaces, such as boiler tubes or the like, to be heated. The flowing heat remains uniform across the entire width of the furnace and the boiler assembly, and thereby avoids stratification. The practice has been, in relatively large furnaces'of the described class, to provide two or more cells in side by side relation, each containing a fuel pile and fire therein, for the purpose of keeping the fire in one cell burning while the ashes were being removed from the remaining cell, thus allowing only a partial pressure drop in the boiler. By reason of the constantly burning fuel pile of uniform size and width in the present invention, there is no appreciable pressure drop in the boiler, either when adding fuel or removing ashes.

Hearth furnaces, generally, burn inexpensive fuels and waste materials which are added in particle form to the fuel pile as needed for main-' taining boiler pressure. Most of the fuel used is usually moist and must be dried before it can be burned. As will become apparent from the following description, the present invention not only provides for drying the fuel, but also provides for storageof the same during the drying process.

In the form of the invention shown, the numeral Ill generally designates a hearth furnace connected with the front of a boiler assembly l l which includes a steam drum [2, lower drum 53, front, intermediate, and rear boiler tubes Hla, Nb, and I40, all connected with each other in the usual manner. cludes front, rear and side walls l5, l6 and I1, respectively, together with a top l8 which encloses the steam drum 12. A damper box [9 con taining dampers therein is located in the upper rearward part of the top I 8. The lower drum i3 is supported on a boiler support 2! mounted on a platform or raised floor 22 secured between the rear wall l6 and an inner wall 23, a baffle 24 extends upwardly from the inner wall 23 and be hind the intermediate tubes [4b, and a similar bafile 24a depends from the top l8 between the intermediate tubes Mb and the rear tubes I40. Both said bafiies 24 and 2% are arranged to permit passage of hot gases around their respective ends. The floor 25, inner wall 23, and the side walls I! are lined with refractory material, as at 26, 2! and 28, to provide a combustion chamber 29. Any suitable refractory material, such as fire brick, not shown in detail, may be used. It is to be understood that the boiler assembly I l is typical, and comprises no part of the present invention, but is herein described to illustrate the utility of the hearth furnace It.

The hearth furnace 10 includes a front wall having a refractory liner 3|, a floor 32, also covered with refractory material 33, and side walls 34 lined with refractory material 35. The side of the floor 32 opposite the front wall 39 is provided with an upwardly projecting bridge wall 35 which is also covered with refractory material 31. There is a transverse air chamber 33 extending through the bridge Wall 36 and is connected with the interior of the hearth furnace lit by' means of tuyeres 39, in the manner illustrated in'Figures l and 2. Across the front wall 30 and at the lower end thereof, there is a transverse air chamber 40 connected with a source of primary air by means of a duct 4|. Any suitable means may be used for forcing air into the last described air chamber 40, from where it is communicated with The assembly H also inthe interior of the hearth furnace by means of tuyeres 42 extending through the refractory material 3! of the front wall 39. Air is also conveyed from the front air chamber 46 to the air chamber 38 in the bridge wall 36 by means of ducts 43 connected therebetween and extending through the hearth furnace floor 32. Secondary air is supplied to the combustion chamber 29 by means of a cross duct ie extending through the bridge wall 35, rearwardly of the air chamber 38 therein, and communicating with the atmosphere. The duct 44 is connected with the combustion chamber 23 by means of additional tuyeres 45 in the rearward side of the bridge wall 35.

The hearth furnace roof of refractory material 45 covers the floor 32 and the refractory material thereon, and is suspended in position by means of hangers 4! connected with an outer roof or cover cs of steel or the like and supported by the front wall and the side walls 34. The inner end of the roof 46 is downwardly, thence upwardly curved where it joins the lower front wall i5 of the boiler assembly i i. The curve referred to forms a nose 69 which is positioned rearwardly of and spaced from the upper surface of the bridge wall 36. Spaced fuel feed holes 50, in the form of flanged cast iron ducts, are vertically positioned through the hearth furnace roof 46 and through the cover 48, and are in spaced alignment with each other above the transverse center of the hearth furnace floor 32. The feed holes 50 provide for dropping fuel therethrough to form a fuel pile 5i on the floor 32 and extend from one side wall liner to the other.

Secondary air may also enter the hearth furnace ID by way of the feed holes 58.

In the form of the invention shown, there are two doors 52 in each wall 34 and positioned opposite the ends of the lower edges of each side of the fuel pile 5! whereby ashes, which fall downwardly from the pile, may be raked out. However, it is to be understood that within the scope of the present invention only one door need be positioned at the end of each lower side of the pile 5i. P'eepholes 53 are provided in the front and side walls 39 and 34 of the hearth furnace l0 for observing the fuel pile 5| to determine whether or not additional fuel is required, and whether or not the ashes falling to the side thereof need to be removed.

In operation, additional fuel is provided through the feed holes as required, and the ashes falling to the sides of the cross pile 5| are removed as required. The added fuel on the top of the stack is dried by the fire and burns when it becomes dry. The pile 5| itself provides for ample storage whereby the fire may be maintained without frequently replenishing the fuel. By reason of the described construction, a uniform continuous flow of heat is conveyed through the tlu'oat 54, formed by the top of the bridge wall 38 and the roof nose 49, into the combustion chamber 23, and upwardly between the forward boiler tubes 14, thence outwardly through the damper box 58. Since the fire from the pile 5! is continuous, and may be added to as required and the ashes removed therefrom without disturbing the flame, there is no appreciable pressure drop in the steam boiler 12 during such operations.

The present invention is not limited to the construction herein shown and described, but may be made in many ways within the scope of the appended claims.

What is claimed is:

1. In a hearth furnace, a substantially rectangular floor adapted to support waste material fuel, thereon, a front wall and opposing sidewalls around three sides of said floor, a roof supported on said walls and positioned over said floor, said roof including fuel feed holes therethrough and arranged substantially over the center of said floor along an imaginary line extending from one said side wall to the other said side wall, a bridge wall along the side of said floor opposite said front wall, the top of said bridge wall being spaced below said roof, at least one clean-out door in each said side wall, one of said doors being arranged adjacent said front wall and the remaining said door being arranged adjacent said bridge wall.

2. In a hearth furnace, a substantially rec tangular floor adapted to support waste material fuel thereon, a front wall and opposing side walls around three sides of said floor, a roof supported on said walls and positioned over said floor, said roof including fuel feed holes therethrough and arranged substantially over the center of said fioor along an imaginary line extending from one said side wall to the other said side wall, a bridge wall along the side of said floor opposite said front wall, the top of said bridge wall being spaced below said roof, two cleanout doors in at least one said side wall, one of said doors being arranged adjacent said front wall and the remaining said door being arranged adjacent said bridge wall.

3. In a hearth furnace, a substantially rectangular floor adapted to support waste material fuel thereon, a front wall and opposing side walls around three sides of said floor, a roof supported on said walls and positioned over said floor, said roof including fuel feed holes therethrough and arranged. substantially over the center of said floor along an imaginary line extending from one said side wall to the other said side wall, a bridge wall along the side of said floor opposite said front wall, the top of said bridge wall being spaced below said roof, two cleanout doors in each said sidewall, one of said doors in each said side wall being arranged adjacent said front Wall and the remaining said doors being arranged adjacent said bridge wall.

IVAN E. CUSHING. GIBBS M. SLAUGHTER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 425,821 Nogar Apr. 15, 1890 1,011,312 Blake Dec. 12, 1911 1,040,868 Bradley Oct. 8, 1912 1,198,179 Beer Sept. 12, 1916 FOREIGN PATENTS Number Country Date 878,478 France Oct. 12, 1942 

